117. It is the same with space. Its representation is not its idea. The representation is always presented to us as something determinate, with a clearness like that of the air illuminated by the sun, or a blackness like the darkness of night. There is nothing of this sort in the idea, or when we reason upon extension and distances.
The idea of space is one; its representations are many. The idea is common to the blind man and to him who sees. For both it is equally the basis of geometry, but the representation is very different in these two. The latter represents space as a confused reproduction of the sensations of sight; the blind man can only represent it as a confused repetition of the sensations of touch.
The representation of space is only indefinite, and even this progressively. The imagination runs over one space after another, but it cannot at once represent a space without limits; it can no more do this than the sight can take in an endless object. The imagination is a sort of interior sight, it reaches a certain point, but there it finds a limit. It can, it is true, pass beyond this limit, and expand still farther, but only successively, and always with the condition of encountering a new limit. Space is not represented as infinite, but as indefinite, that is to say, that after a given limit there is always more space, but we can never advance so far as to imagine an infinite totality. It is the contrary with the idea; we conceive instantaneously what is meant by infinite space, we dispute on its possibility or impossibility, we distinguish it perfectly from indefinite space, we ask if it has in reality limits or not, calling it in the first case finite, in the latter infinite. We see in the word indefinite the impossibility of finding limits, but at the same time we distinguish between the existence of these limits, and finding them. All this shows that the idea is very different from the representation.
To regard space as a mere condition of sensibility is to confound the two aspects under which extension should be considered, as the basis of sensations, and as idea; as the field of all sensible representations, and as the origin of geometry. I have often insisted on this distinction, and shall never weary of repeating it; because it is the line which divides the sensible from the purely intellectual order, and sensations from ideas.
CHAPTER XVII.
INABILITY OF KANT'S DOCTRINE TO SOLVE THE PROBLEM OF THE POSSIBILITY OF EXPERIENCE
118. I think that Kant's Transcendental Æsthetics, or theory of sensibility, is not sufficiently transcendental. It is too much confined to the empirical part, and does not rise to the height which we should expect from the title. The problem of the possibility of experience which Kant proposed to solve, either is not at all touched by his doctrine, or else it is solved in a strictly idealist sense. It leaves the problem untouched, if we consider only what relates to observation; for he only repeats what we already knew in establishing the fact of the exteriority of things; it solves the problem in a strictly idealist sense, inasmuch as these things are only considered as phenomena or appearances.
119. A purely subjective space either does not explain the problems of the external world, or it denies them in denying all reality. What progress has philosophy made by affirming that space is a purely subjective condition? Before Kant, did we, perchance, not know that we had perception of external phenomena? The difficulty was not in the existence of this perception attested by consciousness; but in its value to prove the existence of an external world, in relation with it. The difficulty was in the objective, not the subjective part of the perception.
120. To say that the perception is nothing more than a condition of the subject, is to cut the knot instead of untying it. It does not explain the manner of the possibility of experience, but denies this possibility.
What is experience if there is only the subject? There will be the phenomenon or appearance of objectiveness, but nature is then only a mere appearance, and there is nothing in reality which corresponds to our experimental perceptions. We then have experience reduced to the perception of appearances; and as even this purely phenomenal experience is only possible by virtue of a purely subjective condition, the intuition of space; all experience remains purely subjective, and we find ourselves holding the system of Fichte, admitting the me as the primitive fact, the development of which constitutes the universe. Thus the system of Fichte follows from Kant's doctrine; the former has only carried out the principles of his master.
121. In order to make the connection between the two doctrines still clearer, we shall make some further reflections on Kant's system. If space is something purely subjective, a condition of the sensibility and of the possibility of experience, it follows that the mind instead of receiving any thing from the object, creates whatever is in the object, or rather, whatever we consider as in it. Things in themselves are not extended; extension is only a form with which the mind clothes them. In the same manner, they are not colored, sonorous, tasteful, or odorous, except inasmuch as we transfer to them that which is in ourselves alone. Every thing being reduced to mere appearances, there is in the external world not even the principle of causality of subjective extension; the mind gives it to objects, does not receive it from them. These objects are pure phenomena; and, consequently, the soul only sees what it contains in itself, it knows no other world than that which is its own creation. Thus, we see the real world spring from the me; or, rather, the real world is only the ideal creation of the mind. On this supposition, the laws of nature are only the laws of our own mind, and instead of seeking for the types of our ideas in nature, we ought to regard our ideas as the generative principle of all that exists, or seems to exist; and the laws of the universe are merely the subjective condition of the me applied to phenomena.
122. Some of the disciples of Kant show no fear of his idealist tendencies; in fact they accept them without any hesitation, as may be seen by the comparisons which they use in explaining his doctrine. If a seal be applied to a piece of soft wax, it will leave its impression on the wax; if we suppose the seal to be capable of perception, it would see its mark on the wax, and attribute to the object what it had itself given it. If a vase full of water were capable of perception, it would attribute to the water the form, which in reality is only the form of the vase itself, and is communicated from it to the water. In a similar manner the mind constructs the external world, giving to it its impression and form, and then believing it has received from the external world what it has itself communicated to it.
123. Still we must confess that Kant, in the second edition of his Critic of Pure Reason, rejects these conclusions, and expressly combats idealism. There is no necessity of examining how far the second edition contradicts the first: it is sufficient for me to inform the reader that this contradiction exists, and that in the first edition there are expressions which so plainly lead to idealism, that it is impossible not to be surprised on finding the same author in the second edition of his work strongly opposing the idealist system. I have pointed out the consequences of the doctrine; if the author understood it in a different sense from that which his words expressed, this is merely a personal, not a philosophical question.(31)
CHAPTER XVIII.
THE PROBLEM OF SENSIBLE EXPERIENCE
124. The great problem of philosophy does not consist in the explanation of the possibility of experience; but in establishing the reason of the consciousness of experience, as experience. Experience in itself is a fact of our soul attested by consciousness, but to know that this fact is a fact of experience, is something very different from mere experience; for, by knowing this, we pass from the subjective to the objective, referring to the external world what we experience within us.
We refer objects to different points of space, and regard them as outside of, and distinct from, each other: to say that the instinct by which we so regard them is a condition of the subject and of sensible experience is to establish a sterile fact. The difficulty is in knowing why we have this instinct; why the representation of an extension is in our soul; and why this subjective extension in a simple being should be presented to our perception as the image of something external and really extended.
125. Transcendental esthetics may determine the following problems:
I. To explain what is the subjective representation of extension, abstracted from all that is objective.
II. Why this representation is found in our soul.
III. Why a simple being contains in itself the representation of multiplicity, and an unextended being the representation of extension.
IV. Why and how we pass from ideal to real extension.
V. To determine how far we may apply to extension what is true of the other sensations, which are considered as phenomena of our soul, having no external object like them, and no other correspondence with the external world than the relation of effects to their cause.
126. What is the subjective representation of extension, abstracted from all that is objective? It is a fact of our soul; no further explanation is possible; he that has it, knows what it is; he that has it not, does not, except intelligences of a higher order, which know what this representation is, without experiencing it as we do.
127. I do not pretend that it is possible to explain why the representation of extension is found in our soul; we might as well ask why we are intelligent and sensible beings. The only reason a priori which we can give, is that God has so created us. This representation may be found in us, and it is so found, for we experience it; but this internal experience is the limit of philosophy; immediate observation can go no farther back. Reason raises us to the knowledge of a cause which created us, but not to a phenomenon which is the source of the phenomena of experience.
128. Why a simple being contains in itself the representation of multiplicity, and an unextended being the representation of extension, is the problem of intelligence, which, because it is intelligence, is one and simple, and capable of perceiving multiplicity and composition.
129. We pass from ideal to real extension by a natural and irresistible impulse, which is confirmed by the assent of reason. This has been demonstrated in the first book, and also in the second when treating of the objectiveness of sensations.
130. Of the five problems the last remains. We must determine how far we may apply to extension what is true of the other sensations, which are considered as phenomena of our soul, having no external object like them, and no other correspondence with the external world than the relation of effects to their cause.
131. The solution of this problem settles the question for or against the idealists. If we may apply to extension what is true of the other sensations, idealism triumphs, and the real world, if it exists, is a being which has no resemblance to the world which we think.
I have proved in treating of sensations49 that extension is something real, and independent of our sensations, and I have shown50 that it represents multiplicity and continuity. This is sufficient to overthrow idealism, and also to explain, to a certain extent, what extension consists in; but as the idea of space, which is closely connected with extension, had not then been examined, it was not possible for us to rise above the order of phenomena and regard extension under a transcendental aspect, examining it in itself, abstracted from all its relations with the world of appearances. This is what I propose to do in the following chapters.
132. We come now to a more cragged path; we have to distinguish the reality from appearance; our understanding, which is always accompanied by sensible representations, must now depart from them, and place itself in opposition to a condition to which it is naturally subjected in the exercise of its functions.
CHAPTER XIX.
EXTENSION ABSTRACTED FROM PHENOMENA
133. That which is extended is not one being only; it is a collection of beings. Extension necessarily contains parts, some outside of, and consequently distinct from, others. Their union is not identity; for, the very fact that they are united, supposes them distinct, since any thing is not united with itself.
It would seem from this that extension in itself and distinguished from the things extended, is nothing; to imagine extension as a being whose real nature can be investigated is to resign one's self to be the sport of one's fancy.
Extension is not identified in particular with any one of the beings which compose it, but it is the result of their union. This is equally true whether we consider extension composed of unextended points, or of points that are extended but infinitely divisible. If we suppose the points unextended, it is evident that they are not extension, because extended and unextended are contradictory. Neither are these points identified with extension, if we suppose them extended; for extension implies a whole, and a whole cannot be identified with any of its parts. If a line be four feet long, there cannot be identity between the whole line and one of its parts a foot long. We may suppose these parts, instead of a foot, to be only an inch in length, and we may divide them ad infinitum, but we shall never find any of these parts equal to any of its subdivisions. Therefore, extension is not identical with any of the particular beings which compose it.
134. The idea of multiplicity being involved in the idea of extension, it would seem that extension ought to be considered, not as a being in itself, but as the result of a union of many beings. This result is what we call continuity. We have already seen51 that multiplicity is not sufficient to constitute extension. It enters into the idea of number, and yet number does not represent any thing extended. We also conceive a union of acts, faculties, activities, substances, and beings of various classes, without conceiving extension, and yet multiplicity is a part of all these conceptions.
135. Therefore continuity is necessary, in order to complete the idea of extension. What, then, is continuity? It is the position of parts outside of, but joined to other parts. But what is the meaning of the terms, outside of, and joined to? Inside and outside, joined and separated, imply extension, they presuppose that which is to be explained; the thing to be defined enters into the definition in the same sense in which it is to be defined. Exactly; for, to explain the continuity of extension is the same as to show the meaning of the terms inside and outside, joined and separated.
136. We must not forget this observation, unless we wish to accept the explanations which are found in almost all the books on the subject. To define extension by the words inside and outside, is not to add any thing, under a philosophic aspect; it is merely to express the same thing in different words. Without doubt this language would be the simplest, if all we wanted was to establish the phenomenon only, but philosophy will not be satisfied with it. It is a practical, not a speculative, explanation. The same may be said of the definition of extension by space or places. What is extension? – the occupation of place: – but, what is a place? – a portion of space terminated by certain surfaces: – what is space? – the extension in which bodies are placed, or the capacity to receive them. But even admitting the existence of space as something absolute, what is the capacity of bodies to fill space? Who does not see that this is to define a thing by itself, a vicious circle? The extension of space is explained by the capacity of receiving; the extension of bodies by the capacity of filling. The idea of extension remains untouched; it is not defined, it is merely expressed in different words, but which mean the same thing.
To suppose the existence of space as something absolute, does not help the question, and is, besides, an entirely gratuitous supposition. To take the extension of space as a term by relation to which we may explain the extension of bodies, is to suppose that to be found which we are looking for.
We run into the same error if we try to explain the words inside and outside, by referring them to distinct points in space, we should define a thing by itself; for, we have the same difficulty with respect to space to determine the meaning of inside and outside, joined and separated, and contiguous and distant. If we presuppose the extension of space as something absolute, and try to explain other extensions by relation to this, we only make the illusion more complete. We have to explain extension in itself, the extension of space must be explained as well as the rest; to presuppose it is to assume the question already solved, not to solve it.
137. Extension in relation to its dimensions seems to be independent of the thing extended in the same place. An extension may remain absolutely fixed with the same dimensions, notwithstanding the change of place of the thing extended. If we suppose a series of objects to pass over a fixed visual field, the things extended vary incessantly, but the extension remains the same. If we suppose a very large object to pass before a window, it changes continually; for the part which we see at the instant A is not the part which we see at the instant B, but the extension has not varied in its dimensions. This regards surfaces only, but the same doctrine may be applied to solids. A space may be successively filled with a variety of objects, but its capacity remains the same. There is no identity between the object and the extension which contains it; for any number of objects of the same size may occupy the same place; neither is the air, or any surrounding object, identified with the extension; for these, too, may change without affecting the extension in which the object is contained.
138. Though the dimensions remain fixed while the objects vary, it does not follow that extension is purely subjective, even though we suppose that the objects which vary cannot be distinguished. If the contrary were maintained, the change of the dimensions would prove them to be objective; and the argument might be retorted against our adversaries. That the dimensions are fixed shows that different objects may produce similar impressions; and therefore we can form an idea of a determinate dimension or figure, without reference to the particular object to which it does, or may correspond. No one will deny that we have the representation of dimensions, without necessarily referring them to any thing in particular; but what we wish to determine is, whether these dimensions exist in reality, and what is their nature, independently of their relations to us.
139. If we admit that continuity has no external object either in pure space or in bodies, what becomes of the corporeal world? It is indeed to a collection of beings which in one way or another, and in a certain order, act upon our being.
The difficulties against the realization of phenomenal continuity are not destroyed by appealing to the necessities of the corporeal organization of sensible beings. If any one should ask how external beings can act upon us, and affect our organs, if they have not in them the continuity with which they are presented to us; such a one would show that he does not understand the state of the question. For it is evident that if we should take from the external world all real continuity, leaving only the phenomenal, we should at the same time take it from our own organization, which is but a part of the universe. There is here a mutual relation and sort of parallelism of phenomena and realities which mutually complete and explain each other. If the universe is a collection of beings acting upon us in a certain order, our organization is another collection of beings, receiving their influence in the same order. Either both are inexplicable, or else the explanation of one involves the explanation of the other. If that order is fixed and constant, and its correspondence remains the same, nothing is changed, no matter what hypothesis is assumed in order to explain the phenomenon.
140. The object of our searches here, is the reality subject to the condition of explaining the phenomenon, and not contradicting the order of our ideas.
It might be objected to those who take from the external world the phenomenal or apparent qualities of continuity, that they destroy geometry, which is based on the idea of phenomenal continuity. But this objection cannot stand; for it supposes the idea of geometry to be phenomenal, whereas it is transcendental. We have already shown that the idea of extension is not a sensation, but a pure idea, and that the imaginary representations by which it is made sensible are not the idea, but only the forms with which the idea is clothed.
141. All phenomenal extension is presented to us with a certain magnitude; geometry abstracts all magnitude. Its theorems and problems relate to figures in general abstracted absolutely from their size, and when the size is taken into consideration it is only in so far as relative. Of two triangles of equal bases that which has greater altitude has the greater surface. Here the word greater relates to size, it is true; but to a relative, not to any absolute size; the question is not of the magnitudes themselves, but of their relation. Consequently, the theorem is equally true whether the triangles are immense, or infinitely small. Therefore, geometry abstracts absolutely all magnitudes considered as phenomena, and makes use of them only in order to assist the intellectual perception by the sensible representation.
142. This is an important truth, and I shall explain it further when combating Condillac's system in the treatise on ideas, where I shall show that even the ideas which we have of bodies neither are, nor can be, a transformed sensation. According to these principles, geometry is a science which makes its pure ideas sensible by a phenomenal representation. This representation is necessary so long as geometry is a human science, and man is subject to phenomena; but geometry in itself and in all its purity has no need of such representations.
143. In order that this doctrine may seem less strange, and may be more readily accepted, I will ask, whether pure spirits possess the science of geometry? We must answer in the affirmative; for, otherwise we should be forced to conclude that God, the author of the universe and greatest of geometricians, does not know geometry. Does God, then, have these representations, by the aid of which we imagine extension? No; these representations are a sort of continuation of sensibility which God has not; they are the exercise of the internal sense, which is not found in God. St. Thomas calls them phantasmata, and says they are not found in God, or in pure spirits, nor even in the soul separated from the body. Therefore, the science of geometry is possible, and does really exist without sensible representations, and, consequently, we may distinguish two extensions, the one phenomenal, and the other real, without thereby destroying either the phenomenon or the reality, so long as we admit the correspondence between them; so long as we do not break the thread which unites our being with those around us; so long as the conditions of our being harmonize with those of the external world.(32)